1. Field of the Invention
This invention concerns a method of protecting a wooden structure from infestation with wood-boring marine organisms and in particular, concerns an improved method wherein such a structure is surrounded by a protective barrier.
2. Prior Art
As noted by B. Gulliksen, "Marine Boring and Fouling Organisms", Fauna, Vol. 27, No. 4, p. 185-195 (Oslo) 1974, wood-boring marine organisms have presented mankind with a world-wide problem since ancient times. The ancient bard Homer and the great explorer Columbus were familiar with the hazards presented by these wood-borers. An example of such a destructive organism is the Teredo worm, or shipworm, which has been known to infest wooden structures, such as pilings, rafts, log floats and the like, to such an extent that the wood loses its strength and becomes so eaten away that the structures lose their buoyancy and sink.
Various methods have been suggested for overcoming the marine-borer problem. The most common solution has been the use of creosote-impregnated wood. Impregnation or coating of the wood with resins or other preservative substances or treatment of the wood with substances which are toxic to the borers, have been suggested. The use of eucalyptus wood has been reported to provide satisfactory results. A sheathing of the wood with Muntz metal (i.e., a brass alloy containing 60% copper and 40% zinc) has also been used in the past. Although each of the methods are reported to have met with some success in combating the problem of shipworm infestation, these methods are not totally satisfactory because of the high cost, odor, and toxicity of the various impregnants, preservatives and coatings, the unavailability of special woods, and the difficulty of installation and high cost of metal sheathing. Most of these problems are exacerbated in remote logging camps, where shipworms are an especially costly nuisance.